JPH10211748A - Platen gap adjusting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a gap by moving a recording head up and down in parallel to a printing reference surface. SOLUTION: This apparatus is constituted so that a gap adjusting unit on a paper discharge roller shaft 8 driven by a paper feed motor is displaced toward the meshing side with an intermediate gear 20 by the transfer of a carriage 1 to a platen gap adjusting unit and one of planetary gears 17, 18 is meshed with the intermediate gear 20 by the rotary direction of the paper feed motor. Corresponding to the rotary direction thereof, a pair of guide rods 3, 4 are rotated in the same direction by the same quantity through a fan-shaped gear 25 to displace the carriage 1 in parallel to a printing reference surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platen gap adjusting device for adjusting a distance between a platen and a recording head according to the thickness of a recording medium.

[0002]

2. Description of the Related Art A platen gap adjusting device for adjusting the distance between a platen and a recording head in accordance with the thickness of a recording medium generally includes a pair of guide members g1 for guiding a carriage c as shown in FIG. , G2, the guide member g1 on the side closer to the recording head h is rotated to change the distance of the recording head h from the platen surface or the printing reference position by the amount of displacement of the eccentric shaft.

For this reason, in the conventional printer, before and after the gap adjustment, the recording head h rotates around the other guide member g2 by an angle △ θ corresponding to the gap adjustment amount δ, and the recording medium s is As a result of the deviation of the parallelism between the recording head h and the surface by the angle ズ θ, not only the inconvenience that the printing position is displaced in the line direction and the image is deformed long in the line direction, but also the color In a printer for forming an image, there is a problem that a color tone or the like is affected.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem.
An object of the present invention is to provide a new platen gap adjusting device which does not affect an image before and after the gap adjustment. It is another object of the present invention to provide a new platen gap adjusting device capable of automatically and in parallel moving a recording head to an optimum position with respect to a recording medium.

[0005]

That is, according to the present invention, as a platen gap adjusting device for achieving the above object, a pair of guide members for carriage traveling is rotatably mounted on a printer main body via an eccentric portion. At the same time, the guide member is coupled to an adjusting means for imparting the same amount of rotational displacement, so that the carriage is separated and approached in parallel with the printing reference plane. As means, adjusting means for rotating these guide members forward and reverse in the same direction by the same amount in accordance with the forward rotation and reverse rotation of the paper feed drive means is engaged and disengaged with both guide members in conjunction with the movement of the carriage. It is intended to be.

[0006]

Embodiments of the present invention will be described below. The drawings all show one embodiment of the present invention. First, a printer which operates an ink jet recording system equipped with a platen gap adjusting mechanism according to the present invention will be described with reference to FIG.

[0007] In the figure, reference numeral 1 denotes a carriage for moving a recording head carried thereon in the beam direction.
The two front and rear guide rods 3 and 4 which are guided in the same direction are biased in the same direction, and are rotatably attached to a guide frame (not shown) via eccentric pins 3a and 4a provided at both ends thereof. The carriage 1 is rotated by the carriage adjustment unit 10 in the same direction to support the carriage 1.
Are arranged to be separated and approached in parallel with the platen or the printing reference plane p when there is no platen. In the drawing, reference numeral 6 indicates a paper feed roller, and reference numeral 7 indicates a discharge roller.

FIGS. 1 to 4 show a gap adjusting unit 10 according to an embodiment of the present invention. The gap adjusting unit 10 is connected via a unit frame 11 to one side frame of a printer main body (not shown). , Which is operated by the carriage 1 that has moved there, and is driven by a paper feed motor (not shown) to rotate the two front and rear guide rods 3 and 4 by the same amount. .

Next, the gap adjusting unit 10 will be described in detail. A discharge roller shaft 8 which is driven by a paper feed motor (not shown) and rotates integrally with the discharge roller 7 will be described.
The switching lever 1 which is pushed by the carriage 1 and is displaced to an engagement position with an intermediate gear 20 described later
3 is pivotally supported slidably and rotatably in the axial direction while always being held at the non-meshing position by the urging force of the spring 19 interposed between the unit 3 and the unit frame 11.

The switching lever 13 has, in its center,
A sun gear 16 is slidably mounted on the angular shaft portion 8a of the paper discharge roller shaft 8. At both ends of the switching lever 13, two planetary gears 1 which are always meshed with the sun gear 16 are provided.
When the carriage 7 is displaced by being pressed by the carriage 1, the intermediate gear 20 transmits one of the rotations for adjusting the gap to the intermediate gear 20 according to the rotation direction of the paper feed motor. Is configured.

On the other hand, as shown in FIG. 3, the intermediate gear 20 has two stepped toothless gears having a phase difference so as to selectively mesh with each of the two planetary gears 17 and 18. Parts 21, 22 and a modified Geneva gear part 23 which engages and disengages with a sector gear 25 described later,
The fan gear 25 is configured to rotate by a fixed angle regardless of the amount of rotation of the planetary gears 17 and 18 to rotate the sector gear 25 by a fixed angle.

On the other hand, the sector gear 25 has a shaft end 3 so as to rotate integrally with one of the guide rods 3.
b, and a small sector gear 26 integral therewith meshes with a wing-shaped sector gear 27 disposed between the guide rods 3 and 4, and through this gear 27. It is configured to transmit rotation in the same direction to a small sector gear 28 fixed to the end of the shaft 4b of the other guide rod 4.
In FIG. 4, reference numeral 14 denotes the unit frame 11.
Is engaged with the arcuate engagement hole 12 provided in the
3 shows a claw provided on the back surface of the switching lever 13 for always holding the position 3 in the non-meshing position.

In the embodiment constructed as described above, in a normal use state in which recording and writing is performed on plain paper, as shown in FIGS.
Eccentric pin 3 via small sector gears 26 and 28 that mesh with
By rotating the two guide rods 3 and 4 so that the positions a and 4a are substantially horizontal, the recording head 2 holds a gap suitable for the thickness of the plain paper.

In this state, as shown in FIG. 4, the claw pieces 14 projecting from the rear surface of the switching lever 13 engage with the arc-shaped holes 12 of the unit frame 11 to indicate the switching lever 13 by a solid line. In the non-meshing position.

Then, in this state, an operation button on a panel (not shown) is pressed in order to perform recording and writing on thick recording paper such as color dedicated paper or postcard, or the platen gap can be changed from a personal computer. The carriage 1 which has been moved to the platen gap switching position at the beginning of recording and writing by the instruction presses a part of the switching lever 13 by its protruding end portion 1a, and this is engaged with the engagement shown by the two-dot chain line in FIG. Displace to position.

On the other hand, a paper feed motor (not shown) rotates the paper discharge roller shaft 8 in the counterclockwise direction in FIG. 2 and the switching lever 13 via planetary gears 17 and 18 meshing with the sun gear 16 at the shaft end. Is rotated in the counterclockwise direction, one of the planetary gears 17 is meshed with the intermediate gear 20 and is rotated in the direction of the arrow in the figure, and the sector gear 25 is meshed with the modified Geneva gear portion 23 of the intermediate gear 20. To the stopper 23a
The guide rod 3 is rotated clockwise in the drawing while being rotated by a predetermined amount to a position where the guide rod 3 is brought into contact with the fan gear 25. The sector gear 27 is turned in the direction of the arrow in the figure, and the other guide rod 4 is turned in the same direction via the other small sector gear 28 meshing therewith. Is pulled up in parallel with the printing reference plane p.

It is needless to say that the platen gap can be adjusted by rotating the paper feed motor in the opposite direction to the case where thin recording paper is used. In the above-described embodiment, the carriage 1 is configured to be automatically displaced in parallel with the printing reference plane p via the guide rods 3 and 4 by the paper feed motor. Alternatively, the two front and rear guide rods 3, 4 may be manually displaced in the same direction so that the recording head 2 itself is displaced in parallel.

[0018]

As described above, according to the present invention, the same amount of rotational adjustment is made to the pair of carriage traveling guide members attached to the printer body via the eccentric part. The carriage supported and guided by these guide members can always be adjusted in parallel according to the thickness of the recording medium and the like, so that the print quality is always kept constant irrespective of the gap adjustment. be able to.

In addition, the adjusting means for adjusting the carriage in the same direction in the same direction in accordance with the forward and reverse rotation of the paper feed driving means in the same direction as the carriage is engaged with and disengaged from the guide member in conjunction with the movement of the carriage. With this configuration, this kind of gap adjustment can be automatically adjusted only when it is adjusted according to the recording medium to be printed.

[Brief description of the drawings]

FIG. 1 is a side view of a platen gap adjusting device according to an embodiment of the present invention in a normal state.

FIG. 2 is a side view of the same device showing a state where a gap is largely adjusted.

FIGS. 3 (a) and 3 (b) are a plan view and a cross-sectional view of an intermediate gear used in the above device.

FIG. 4 is a view of a main part of the same device shown in relation to the movement of the carriage.

FIG. 5 is a diagram illustrating an example of a printer including the above device.

FIG. 6 is a diagram showing a problem of the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 3, 4 Guide rod 10 Gap adjustment unit 16 Sun gear 17, 18 Planetary gear 20 Intermediate gear 23 Deformed Geneva gear part 25 Sector gear 27 Wing sector gear

Claims (2)

[Claims] 1. A pair of guide members for carriage traveling are rotatably mounted on a printer main body via an eccentric portion, and a preparation means for imparting the same amount of rotational displacement to both guide members is connected. A platen gap adjusting device, wherein a carriage is separated and approached in parallel with a printing reference plane. An adjusting means for rotating the guide members forward and backward in the same direction by the same amount in accordance with the forward rotation and the reverse rotation of the paper feed drive means; The platen gap adjusting device according to claim 1, wherein the platen gap adjusting device is detachably attached to the member.